What little I could find on the 17th Enrolled Missouri Militia of the St. Louis area I found in the State of Missouri's "Report of the MO Adjutant General for the Year 1863" on pages 410 and 411. This is merely an officer roster. If you know in which company the individual served I could give your his offiers' names. I could then look them up in the 1860 census and attempt to decipher in what part of the St. Louis area this company originated. By the way, what is the name of the individual you know that served in the 17th EMM?
From what I could see on the officer roster with remarks about their dates of beginning service this regiment was only in existence between late August 1862 (when the EMM program began) until sometime during 1863. There seems to be no record of it after 1863. I know of no active service that this unit served, but, then, the St. Louis area units performed little active service until the crisis in late September 1864 when it appeared General Price's Confederate army of about 12,000 was heading for the city.
Bruce Nichols